How did you create the backup? How do you try to restore it?
Which version of SQL Server do you use? - Are the versions different for backup/restore?
Do you use SQL Server Management Studio? Which version?

2 solutions

Solution 2

when u created backup it may be possible that in the list displayed in bottom you had two different backup files added and now you are restoring with only one file. please check. re create backup after deleting all existing backups. hope it solves your problem. happy to help.........